This invention relates to a crystalline polyester multi-filamentary yarn comprising extra-fine filaments, which possesses ameliorated properties regarding a heat-setting property, a raising or napping property, a dimensional stability, a twist resistance which enables one to employ a higher twist coefficient in the false-twist crimping. This invention also relates to a commingled yarn and a cloth, both of which comprising said crystalline polyester multi-filamentary yarn.
So called extra-fine filaments of 0.9 denier per filament or less have achieved a wide commercial acceptability since said filaments, owing to their preferable hand, are useful for natural skin-like fabrics especially suede-like goods when cloths comprising said filaments are raised.
Heretofore various methods have been proposed for the production of such filamentary yarns or fibres. There are (a) to dissolve a sea component out of sea-island type conjugated yarns, (b) to split side-by-side type conjugated yarns, (c) to cause extruded filaments flow-drawing for the purpose of obtaining leant filaments followed by neck-drawing, (d) to make leant filaments by use of a conventional spinning and drawing process, and (e) to obtain oriented extra-fine filaments by use of a high speed spinning step of more than 3000 meters/minute.
Of those processes mentioned above, (a) and (b) are considerably expensive because they requires not only a special and complicated spinning device but also two or more different polymers and an additional tedious step to dissolve out the sea component and to split resulting fibrils consisting of island components. In the processes of (c) and (d), it is rather difficult to produce desired filaments of 0.9 denier per filament or less due to frequent and increasing occurrence of yarn breakage as the filaments decreases in fineness during the drawing operation and the denier variation is unavoidably enhanced even if the fine filaments may be obtained occasionally.
On the other hand, the high speed spinning process according to (e) bears an advantage to produce fine filaments in simplicity and further without causing particular problems.
The inventors have found, in the course of research for preparing extra-fine filaments by mean of the high speed spinning process for the purpose of making the most use of said process, that a crystalline polyester multifilamentary yarn can be prepared which presents various peculiar properties never conceived in conventional yarns heretofore produced. Further the said yarn finds its use as for silky or velours-like goods by using the same in the form of a commingled yarn with other filaments, and also its use as for raised, crepe (crepon georgette inclusive) and anti airpermeative goods having an improved hand as well as appearance by subjecting a cloth comprising said crystalline filamentary yarn to a proper finishing operation.